Plastic memory cards developed

Researchers have developed a conducting plastic that has the potential to store a megabit of data in a millimetre-square device (10 times denser than current magnetic memories). They expect this device to be a cheap and fast memory card, but it has one big drawback : it can not be rewritten.

The device sandwiches a blob of a conducting polymer called PEDOT and a silicon diode between two perpendicular wires. Substantial research effort has focused on polymer-based transistors, which could form cheap, flexible circuits, but polymer-based memory has received relatively little attention.

The key to the new technology was the discovery by researchers from Princeton University, New Jersey, and Hewlett-Packard Laboratories in Palo Alto, California, that passing a high current through PEDOT turns it into an insulator, rather like blowing a fuse. The polymers two possible states, conductor or insulator, then form the one and zero necessary to store digital data.

"The beauty of the device is that it combines the best of silicon technology - diodes - with the capability to form a fuse, which does not exist in silicon," says Vladimir Bulovic, who works on organic electronics at the Massachusetts Institute of Technology.

However, turning the polymer INTO an insulator involves a permanent chemical change, meaning the memory can only be written to once. Its creators say this makes it ideal for archiving images and other data directly from a digital camera, cellphone or PDA, like an electronic version of film negatives.